.sl-selectmask {
	position: absolute;
	left:0;
	top:0;
	z-index: 10;
	overflow: hidden;
	width: 33em;
}
.sl-selectmask iframe {
	position: absolute;
	top: 0; 
	left: 0; 
	z-index: -1;
	border:none;
	filter: mask();
	width: 3000px; /* for any big value */
	height: 3000px /* for any big value */
}